Chipless round hole cutter

ABSTRACT

A chipless round hole cutter including a screw shear and die body which cooperate to provide a round hole in a sheet of metal. The die body has an opening equal to the desired opening to be cut in the metal and the die body fits over the screw portion of the screw shear. The screw shear includes a tapered helical threaded section which is used to cut the metal and to carry and guide the cut metal within the groove to be retained in the threaded groove within the die body. The cutting edge of the screw shear adjacent to the die body provides for the final cutting of the hole to the desired size. The screw shear may be tapered along its entire length and with various size die bodies used to provide for a plurality of different size openings with a single screw shear or the screw shear may include a straight threaded section having a diameter substantially equal to the opening through the die body.

Uited States Patent [1 1 Carr [451 Sept. 25, 1973 CHIPLESS ROUND HOLECUTTER [75] inventor: Kelly B. Carr, West Covina, Calif.

[73] Assignee: Carr Engineering Corporation, Los

Angeles, Calif.

[22] Filed: Dec. 22, 1971 [21] Appl. No.: 210,846

[52] US. Cl 408/22, 408/67, 408/199,

408/208, 85/46, 72/71, 30/240 [51] llnt. Cl B231) 51/02, 1323b 51/08[58] lField 01' Search 30/240; 85/46;

[56] References Cited UNITED STATES PATENTS 3,076,356 2/1963 Simich408/223 Primary Examiner-Francis S. Husar Attorney-Charles H. Schwartz 57 ABSTRACT A chipless round hole cutter including a screw shear and diebody which cooperate to provide a round hole in a sheet'of metal The diebody has an opening equal to the desired opening to be cut in the metaland the die body fits over the screw portion of the screw shear. Thescrew shear includes a tapered helical threaded section which is used tocut the metal and to carry and guide the cut metal within the groove tobe retained in the threaded groove within the die body. The cutting edgeof the screw shear adjacent to the die body provides for the finalcutting of the hole to the desiredsize. The screw shear may be taperedalong its entire length and with various size die bodies used to providefor a plurality of different size openings with a single screw shear orthe screw shear may include a straight threaded section having adiameter substantially equal to the opening through the die body;

7 Claims, 2 Drawing Figures a l CHIPLESS ROUND HOLE CUTTER The presentinvention is directed to a chipless round hole cutter for cutting ablind hole from one side of a sheet of metal and with all of the cutmetal brought to the outside so that no contaminants will be present onthe other side of the sheet of metal.

It is often desirable to provide for a hole to be cut through a sheet ofmetal where it is difficult if not impossible to get to both sides ofthe sheet of metal. For example, in the construction of a boiler, it isdesirable to form the boiler as a sealed chamber and withholes then cutinto the wall of the boiler to allow for fittings to be mounted atvarious places on the boiler. Presently, it is necessary to provide forsuch holes to be cut prior to assembly of the boiler or at least beforethe boiler has been completely sealed.

Another area where it is desirable to cut a blind hole is in theinstallation of auxiliary oil filtering equipment for various types ofcombustion engines. For example, it is known that it is desirable toprovide for additional filtering and purifying of oil for an automobileengine. Such devices are available'and are usually connected as a bypassto detour a portion of the oil through these auxiliary filters. Oneconnection to these auxiliary filters is usually from the oil pan. Inorder to make such a coupling to the oil pan, it is necessary to cut ahole in the pan to receive a fitting for a hose coupling to theauxiliary filter.

The present practice is to remove the oil pan to provide access to bothsides of the oil pan so that a standard hole cutter which requiresaccess to both sides may be used to cut the hole. It is obvious thatsuch a procedure is time consuming, thereby greatly increasing the costof the installation of such auxiliary oil filter. However, it would notbe desirable to drill a hole from the exterior of the oil pan since sucha drilling opera tion would undoubtedly provide for contaminants withinthe oil pan and such contaminants could have a deleterious effect on theoil. It is therefore desirable to provide for a round hole cutter whichmay be used from an exterior position and wherein a smooth round holemay be produced ofa desired size and with all excess metal being broughtto the outside so that no contaminants would be present within the oilpan.

The round hole cutter of the present invention includes a screw shearand a cooperating die body. The die body is a cylindrical member havinggenerally a thick wall and with the inside diameter at at least one endof the die body equal to the. size of the hole which is desired to becut in the metal. The screw shear cooperates with the die body byfitting through the die body and having a flange portion to limit theextension of the screw shear through the die body. The forward portionof the screw shear which projects beyond the die body is tapered andincludes a helical thread to act as the cutter for the metal. Theportion of the screw shear adjacent to the end of the die body havingthedesired size opening provides for the final cutter to produce thedesired hole in the sheet of metal.

In one embodiment of the round hole cutter of the present invention, thescrew shear includes a first rearward section which has an outsidediameter substantially equal to the size of the hole to be cut in themetal and with a forward section extending from this single diametersection and having a taper to provide for the cutting of the metal. Asecond embodiment of the round hole cutter of the present inventionincludes a screw shear which is tapered throughout its length and withthe die body having a cooperating tapered opening to receive the screwshear and with the length of the die body controlling the opening to becut in the metal so that, by using a plurality of die bodies havingdifferent lengths, a single screw shear may be used to provide forcutting holes of different diameters. In either embodiment, the spiralof material which is cut as the hole is being formed is pulled upwardlywithin the groove of the helical thread and is retained in the groovesof the screw shear within the die body so that no excess material willbe present on the inside surface of the sheet of metal.

In the operation of the round hole cutter of the present invention, thescrew shear is slipped through the die body to have the tapered portionextend beyond the die body. Initially, a relatively small opening ispunched into the metal so that the tapered end of the screw shear may beinserted in this small opening. The screw shear may now be turned in adirection to provide for a cutting of the metal and in order tofacilitate such a turning of the screw shear, the end of the screw shearopposite to the tapered portion may eithercontain a handle or may beformed as a member including straight sides so as to receive a wrench.At this time, the die body is still maintained loosely on the screwshear and the particular position of the die body is not important.

As the screw shear is turned to continue to cut the metal, the screwshear and die body approach the metal until the die body is pressing upagainst the metal and with the flange portion of the screw shear nowproviding pressure against one end of the die body. The cutting edge ofthe screw shear immediately adjacent the portion of the die body whichis abutting the metal provides for a final cut of the metal to produce around hole and with all of the excess metal cut by the screw shearcontained within the grooves of the screw shear and within the die body.

A clearer understanding of the invention will be had with reference tothe following description and drawings wherein:

FIG. ll illustrates a first embodiment of the invention for providingfor a single size hole in a sheet of metal; and

FIG. 2 illustrates a second embodiment of the invention for providingfor holes of different diameters to be cut in the metal using die bodiesof various length.

In FIG. 1, a first embodiment of a round hole cutter is shown andincludes a die body 10 and a screw shear 12. The screw shear includes afirst taper threaded portion 14, a second threaded portion 16 of asingle diameter and with the threads in the -first and second portions14 and 16 being continuous. The threads may actually be formed as adouble lead screw to provide for a balanced cutting of the sheet metal.Specifically, the threads include a cutting edge and a deep groove toreceive the material as it is cut. The end of the screw shear oppositeto the cutting end is formed as the head of a bolt 18 so as to receive awrench such as a socket wrench. A flange member 20 operates as a stopand bearing surface between the screw shear l2 and the die body 10.

The inner diameter of the die body 12 is substantially equal to the sizehole to be cut and in the embodiment of FIG. 1 the single diameterportion 16 of the screw shear has a length substantially equal to thelength of the die body and with the tapered portion 14 of the screwshear extending from the die body 10 when the die body 10 is fullypositioned over the single diameter portion 16.

In the operation of the round hole cutter of the present invention, asheet metal 22 is to have an opening cut to a particular diameter andwith all excess material removed to the outside. Specifically, a smallhole is punched through the sheet metal 22 so as to insert the forwardend of the tapered portion 14 of the screw shear to initiate the cuttingoperation. The double threads of the tapered portion 14 will cut themetal in a double spiral upon turning of the screw shear 12 in aclockwise direction. The metal that is cut from the sheet metal 22enters the grooves of the threads and is pulled upwardly within thegrooves as the cutting operation proceeds. This can be seen by the metal24 shown in the grooves of the thread of the screw shear.

As the cutting operation continues, the sheet metal 22 is locatedadjacent to the die as shown by the dotted position of the sheet metal22. At this time, the cutting edge 26 performs its final cut to providefor a hole in the sheet metal 22 of the proper diameter. This finalcutting edge cooperates with the edge of the die 10 to produce a cleanround opening in the sheet metal 22 of the desired diameter. All of themetal which has been cut from the sheet metal 22 is now located withinthe groovs of the single diameter portion 16 andis therefore locatedwithin the die 10. Therefore, all of the metal that has been cut isbrought to the outside and is retained there to thereby prevent anycontaminants from being on the inside.

FIG. 2 illustrates a second embodiment of the invention including a diebody 100 and a screw shear 102. The screw shear 102 is taperedthroughout its length and cooperates with a tapered opening in the diebody 100. The screw shear also includes a head portion 104 and a flange106 to cooperate with the die 100 in a manner similar to that describedwith reference to the embodiment of FIG. 1. Specifically, the length ofthe die body 100 determines the opening to be cut in the sheet metal,since the length of the die body 100 determines the inside diameter ofthe die body at the position 108. It can therefore be seen that varioussize holes may be cut in the sheet metal by using die bodies ofdifferent length. For example, as shown by the dotted lines 110, a diebody having a greater length than the die body 100 will provide for asmaller opening to be cut in the sheet metal since the inside diameterof the die body at the position 112 is smaller than the inside diameterof the die body 100 at the position 108.

It can therefore be seen that the present invention provides for asimple structure to produce a round hole in sheet metal from one sideonly of the sheet metal and with all the cut metal brought to the oneside and there being no out metal on the other side of the sheet metal.The structure is simple in that it includes a screw shear and a die bodyand the operation of the round hole cutter is also simple so that it maybe accomplished by labor which is relatively unskilled.

Although the invention has been described with reference to particularembodiments, the invention is only to be limited by the appended claims.

I claim:

1. A round hole cutter, including a die body formed with a centralopening and having an inner diameter at a first end of the die bodysubstantially equal to the hole to be cut,

a screw shear, including a threaded portion having cutting edges andhaving a length greater than the length of the die body,

a flange member providing a stop between the screw shear and the diebody and with the threaded portion inserted into the die body to extendfrom the first end of the die body and with the outer configuration ofthe threaded portion of the screw shear contained within the die bodyand conforming to the inner configuration of the opening through the diebody and with the threaded portion of the screw shear extending from thefirst end of the die body tapered inwardly,

the combination of the screw shear and die body providing for a roundhole to be cut through sheet material and with the cut material pulledupward and contained within the grooves between the threads to therebybring all of the cut material to the outside to be stored in the groovesof the screw shear within the die body.

2. The round hole cutter of claim 1 wherein the portion of the screwshear contained within the die body has a single diameter and the diebody has an opening of a single diameter.

3. The round hole cutter of claim 1 wherein the screw shear is taperedfrom one end to the other and with the die body having a tapered openingcorresponding to the taper of the screw shear and with a plurality ofsuch die bodies of different lengths used to provide for cutting holesof different diameters.

4. A round hole cutter for cutting a round hole through sheet materialand for insertion from a first side of the sheet material and with allof the cut material pulled to the first side, including a die bodyhaving an opening extending therethrough and with the inner diameter ofthe die body at one end substantially equal to the size of the hole tobe cut in the sheet material, and

a screw shear having a helical thread extending from a first end of thescrew shear to a second end and with the screw shear having a lengthgreater than the length of the opening through the die body to providefor a portion of the screw shear extending past the die body when thescrew shear is inserted into the die body and with the portion of thescrew shear extending past the die body tapered and with the portion ofthe screw shear maintained within the die body having an outerconfiguration conforming to the inner configuration of the openingthrough the die body.

5. The round hole cutter of claim 4 wherein the screw shear includes asection contained within the die body of a single diameter and whereinthe opening through the die body is of a single diameter.

6. The round hole cutter of claim 5 wherein the helical thread is formedas a double helix to provide for balanced cutting of the sheet material.

7. The round hole cutter of claim 4 wherein the screw shear is taperedfrom one end to the other and the opening through the die body istapered to conform to the taper of the screw shear.

1. A round hole cutter, including a die body formed with a centralopening and having an inner diameter at a first end of the die bodysubstantially equal to the hole to be cut, a screw shear, including athreaded portion having cutting edges and having a length greatEr thanthe length of the die body, a flange member providing a stop between thescrew shear and the die body and with the threaded portion inserted intothe die body to extend from the first end of the die body and with theouter configuration of the threaded portion of the screw shear containedwithin the die body and conforming to the inner configuration of theopening through the die body and with the threaded portion of the screwshear extending from the first end of the die body tapered inwardly, thecombination of the screw shear and die body providing for a round holeto be cut through sheet material and with the cut material pulled upwardand contained within the grooves between the threads to thereby bringall of the cut material to the outside to be stored in the grooves ofthe screw shear within the die body.
 2. The round hole cutter of claim 1wherein the portion of the screw shear contained within the die body hasa single diameter and the die body has an opening of a single diameter.3. The round hole cutter of claim 1 wherein the screw shear is taperedfrom one end to the other and with the die body having a tapered openingcorresponding to the taper of the screw shear and with a plurality ofsuch die bodies of different lengths used to provide for cutting holesof different diameters.
 4. A round hole cutter for cutting a round holethrough sheet material and for insertion from a first side of the sheetmaterial and with all of the cut material pulled to the first side,including a die body having an opening extending therethrough and withthe inner diameter of the die body at one end substantially equal to thesize of the hole to be cut in the sheet material, and a screw shearhaving a helical thread extending from a first end of the screw shear toa second end and with the screw shear having a length greater than thelength of the opening through the die body to provide for a portion ofthe screw shear extending past the die body when the screw shear isinserted into the die body and with the portion of the screw shearextending past the die body tapered and with the portion of the screwshear maintained within the die body having an outer configurationconforming to the inner configuration of the opening through the diebody.
 5. The round hole cutter of claim 4 wherein the screw shearincludes a section contained within the die body of a single diameterand wherein the opening through the die body is of a single diameter. 6.The round hole cutter of claim 5 wherein the helical thread is formed asa double helix to provide for balanced cutting of the sheet material. 7.The round hole cutter of claim 4 wherein the screw shear is tapered fromone end to the other and the opening through the die body is tapered toconform to the taper of the screw shear.